Why Are Banana Circles Important? What Are The Benefits?

Banana circles are a popular and fairly easy-to-make addition to any tropical permaculture system. As there is already a lot appropriate literature out there on how to make banana circles I will not focus on the practicalities in this article (see for example 1, 2, 3). But why exactly are they so important? Can they be integrated into any system? And what are the benefits? Read on to explore these questions.

Tropical Issues

“In the tropics,” said Bill Mollison, “plough agriculture is totally inappropriate…For a few years we can hold nutrient perhaps but then it will go” (4).

Ploughing anywhere can cause this loss of nutrients but perhaps in the tropics more than anywhere it is important to encourage ecosystem regeneration designs, since tropical climates are so extreme. Hot seasons of months without moisture are followed by “torrential, hot rain” (4), which if the landscape is not efficiently managed can cause much quicker soil degradation than in other climates.

As well as inefficient land management and extreme climate many tropical zones share a similar problem, that of lack of sufficient infrastructure to deal with waste (1). Again, this can be seen as a global problem, as even when you live in a place where there is a service to take away your rubbish, this doesn’t necessarily mean that the rubbish is going to be utilised in an efficient or environmentally-friendly way. In many tropical countries, however, such a service simply doesn’t exist, and so the choices of what to do with perceived rubbish become fewer. Many either take it to the nearest rubbish pile or burn it (see for example 5). When the waste is organic matter this can be an effective, if energy inefficient, solution, but in many places non-biodegradable materials have been introduced into this system, resulting in burning or inefficient disposal of plastics and electronic parts.

A giant golden Buddha overlooks a rubbish pile in central Thailand. Photo by David Ashwanden

Some countries are beginning to address this, for example some states in India have recently banned use of plastic bags, and are attempting to enforce by law that all takeaway food and drink vendors use biodegradable containers (6, 7). However, as well as getting rid of plastic and other materials using fire, in many countries such as South East Asia there is also somewhat of a tradition of burning whole fields and forests. For example, Chiang Mai in Northern Thailand is known for its ‘burning season’ during which time so many fields are set on fire that tourists are warned to stay away and residents wear masks (8). There are many factors affecting the reasons for this burning, including the search for rare and valuable delicacies like mushrooms and red ant eggs and the idea of ‘slash-and-burn’ agriculture being beneficial for the soil (9). The imbalance the burning causes to the ecosystem does not appear to be worth the delicacies, since if such imbalance continues they will stop being available. As for ‘slash-and-burn’, though it has been shown to temporarily improve soil conditions by adding the nutrients from the ash into the soil, the improvement cannot be sustained beyond 2 years or so and is detrimental if done in the same place season after season (10).

Bananas to the Rescue

Luckily the extreme nature of the tropics means that succession can be accelerated so problems can be turned into solutions quickly. A banana circle is one example of this. The ‘problem’ of having lots of organic matter which would otherwise be either transported to a different place or set fire to becomes the solution of being a source of food for your plants, as the circle’s centre is a compost pile to feed the bananas. Banana circles also help to cycle what may otherwise be considered ‘waste’ water into a productive system, and Bill Mollison apparently even recommended “throwing in much of one’s trash since that service is often limited in the tropics and can even be a resource in iron deficient soils” (1).

Recycling plastic and other seemingly unrecyclable rubbish on your own land could at the very least help you to monitor what exactly you are throwing away and thus help you to reduce your material consumption. Also, all materials originally came from the Earth so returning them to the ground may not necessarily be detrimental; the only problem with plastic is that it has existed for such a relatively short time compared to global history that we don’t know what to do with it right now. Plastic originated from organic matter which decomposed millions of years ago to make crude oil (11). Who can imagine what re-buried plastic may change into in centuries’ time? This is not a recommendation to bury your plastic or throw it on the ground, simply a point to consider. Where plastic recycling exists, where you can reuse materials or, if you’re planning to throw them away anyway, not use them in the first place, it is much more energy efficient to do so. The benefits of throwing plastic onto a compost pile would simply be as oppose to burning it in that that the carbon present in the material can be stored in the ground rather than being released as a toxin into the air.

How?

It’s all very well creating compost piles, but what do bananas have to do with it? With banana circles, different elements of the design provide mutual benefit for each other, water is being filtered into the soil, and nutrients are building up. Multiple potential problems are solved with this design: the organic matter and greywater which may have turned into a waste stream or a producer of pollutants become instead rich food for the banana trees and other species in the system. The trees themselves, which normally require a lot of organic material and water inputs, get the benefit of all the nutrients they need without extra input from the gardener.

Who needs banana circles?

The idea is based on using guilds (12) – groups of plants which can help each other to grow – and also utilises ‘multiple functions for each element’ (13) and ‘multiple elements for each function’ (14). Banana circles create a place to put materials in order to reuse them, so for this reason they may not be appropriate for all systems. If we look at it in terms of inputs, outputs and functions, the main inputs are, as mentioned, organic material and water. The whole point of the system having these inputs is that you are creating a place in your system for materials which would not otherwise have one. If you have a lot of organic material but already use it to make compost in a different way, or for another purpose, or if your ‘waste’ water is already cycled through a greywater system such as a reed-bed or natural swimming pool, then making a banana circle may not be energy efficient for you. Similarly, if you do not have much access to used water or organic material a banana circle may not be appropriate. The point is to combine the elements of nutrient- and water-hungry plant species with nutrient- and water-producing ‘waste’ so all of these elements need to be present in order to create a flourishing banana circle.

Looking at the flow

Once you have ascertained whether or not a banana circle is suitable for you the next thing is to go about making it. The technique is similar to that of making swales (see for example 15) in that you are creating a dip in one place which can catch water and using the material from the dip to create a mound in which you can plant the trees. So the first step is to analyse the flow of water on your site and choose a place accordingly. As mentioned, in order to make a truly efficient design the banana circle will probably be catching greywater from a kitchen sink, shower or even the urine from a compost toilet (3), so theoretically you can put the circle anywhere and lead the water from those places to it using a pipe. To save energy and resources, however, it is probably advisable to site it close to the source of the used water if possible.

As well as thinking about where the water is coming from, you may wish to think about where it wants to flow once it arrives in the banana circle. Siting the banana circle in a place where water would naturally gather anyway because of the shape of the land can save a lot of time and energy. It’s fine if the ground slopes slightly (1), though if there is too much of a slope the nutrients may not be available to all the trees around the edge. Ensure that the water is coming in at the top of the slope and the overflow is at the bottom to slow, spread and sink it into the banana circle as effectively as possible.

Digging the circle

The dip in the centre needs to be large enough to hold sufficient nutrients from the central compost pile to feed all of the trees around the edge; or, to reverse this, you need enough trees to feed on the broken-down nutrients so that the pile in the centre can decompose. Doug Crouch of Treeyo Permaculture recommends that the inner circle should be around 2m in diameter and around 66.5cm deep, and that with such simensions the circle can suppirt 5 banana trees (1). Once you have dug this inner circle you can use all of the soil you dug out of the hole to make a mound all the way around the edge. This outer ring should be around 62.5cm wide and 29cm high, making the total diameter of the entire circle 3.25m (1). The outer ring should have a gap for you to walk in to put the organic matter at the centre, and for overflow water to flow out. You are now ready to add the organic material in a mound in the centre, and then to plant up the edges. For more information on how many banana trees to plant, which other species can join the guild, and how to maintain the banana circle, you can check out (1, 2, 3).

Banana Power – A Transferable Energy

Once planted, the trees and other guild plants in the banana circle will start cycling the material immediately. In a tropical environment, as you are giving so much nutrient and water to such fast-growing trees, results will probably be very visible and very fast (see for example 16). Banana circles can be a huge help in creating abundant, regenerative systems to solve some of the problems of soil degradation, waste disposal and water management in the tropics. However, these problems are not just endemic to tropical climates. The blight of ploughing is present in most parts of the world. Although many countries have waste disposal services this does not necessarily mean that the waste is being recycled or used in a beneficial way. Banana circles can be an inspiration for permaculture systems everywhere. In climates other than tropical ones the species will be different and the results may take longer to manifest but as a design framework this can be applied all over the world. For example, Doug Crouch suggests using the design in Mediterranean climates with tamarillo (Solanum Betaceum) and temperate climates with chokeberries (Aronia spp.) (17), and John Kitsteiner recommends the ‘tomato circle’ (18). Wherever you are practicing permaculture, maybe the benefits of this design can help to inspire you.